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An analysis of ancient mitochondrial DNA has cleared up the family tree of the mysterious Macrauchenia patachonica, writes Jana Howden.

Solving an 180-year-old mystery that Charles Darwin himself couldn’t crack, new access to ancient DNA has revealed than an extinct South American mammal that died out around the end of the last ice age is related to the group including rhinos, horses, and tapirs.

In research published in Nature Communications, an international team devised a new way of looking at ancient mitochondrial DNA in order to unravel the mystery of Macrauchenia patachonica, a hoofed mammal thought to have weighed as much as 500 kilograms.

The first fossils of Macrauchenia patachonica were discovered in 1834 by Charles Darwin in Argentina. But neither he nor renowned British palaeontologist Richard Owen were able to place the animal accurately amongst its taxonomic relatives.

The fossil of the extinct mammal analysed in this new research was found in a cave in Southern Chile. Even with modern genetic technologies, working with such ancient DNA can present serious challenges.

Normally, researchers use genetic material from living relatives of the extinct species as a scaffold upon which to piece together segments of DNA scavenged from ancient remains.

But as one of the study’s authors Mick Westbury from the University of Potsdam in Germany explains; “We had a difficult problem to solve here: Macrauchenia doesn’t have any really close living relatives.”

To circumvent this issue, the researchers devised a new approach of analysing the ancient DNA called iterative mapping. The mechanism uses strict parameters and a range of living animals as reference points, allowing the researchers to fill the gaps in the fossil’s genetic makeup.

Using iterative mapping of the mitochondrial DNA found in the fossil, the team were able to correctly read and analyse enough of the extinct mammal’s genetic material to place it in the larger phylogenetic family known as Panperissodactyla.